


Bound

by FellQueen (Nikasha)



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell (Undertale), Fellcest - Freeform, Light BDSM, M/M, Petplay, Shibari, Underfell Papyrus (Undertale), Underfell Sans (Undertale)
Language: English
Status: Completed
Published: 2020-01-26
Updated: 2020-01-26
Packaged: 2021-02-27 05:21:21
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,135
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22421734
Author URL: https://archiveofourown.org/users/Nikasha/pseuds/FellQueen
Summary: Sometimes, Sans’s bark is worse than his bite.
Relationships: Papyrus/Sans (Undertale), Underfell!Sans/Underfell!Papyrus
Comments: 11
Kudos: 74





	Bound

**Author's Note:**

> Secret santa gift for Eruerushi on twitter! Hope you enjoy~

The door slammed shut. Papyrus turned and started closing all the locks and shifting the deadbolt. The clicking was satisfying. When the last fell into place, it was like a weight was lifted off his shoulders.  
He sighed and went over to the couch, dropping onto the worn cushions and rubbing a hand over his brow.  
He lifted his head suddenly, tension setting his body into a tight line again. “Sans?”  
There was a low grumble from the floor at the other end of the couch. Papyrus went slack and stood, moving around to see the other skeleton stretching from his spot on some pillows and a blanket on the floor. Sans blinked sleepily at him and yawned, then sat up.  
Papyrus knelt and gently dragged his claws over the side of Sans’s skull. “Were you guarding the house?” he asked, tone soft and amused.  
Sans nuzzled into the strokes and opened his mouth to reply when the spark of awareness finally hit the red lights of his eyes. Instead of speaking, he just barked and smirked.  
Papyrus chuckled. “Come here.” He moved to sit on the couch and Sans followed, crawling out of his little makeshift den to sit in Papyrus’s lap, shoving his head under the other’s jaw.  
“You sure you are not a cat instead?” he asked amicably, earning a displeased growl. “My mistake. Guard dog.” He scratched along Sans’s jaw and Sans shuddered. Papyrus grabbed his chin and turned his head. Sans grimaced and fought his grip as Papyrus nuzzled into his jaw, then his neck. Sans stilled, every bone in his body still taut as he let Papyrus push his face into his hood. “Good boy,” Papyrus breathed and felt Sans shudder.  
He turned and murmured to him even as Sans continued to strain rebelliously against his grip. “I want to fuck you, but you know my rules. So would you rather stay a dog or play a different game?”  
Sans hissed and growled. He fought Papyrus, clawing at his wrist and leaving dark scratches behind. Papyrus held him until he subsided, panting and confused. He slowly blinked and looked away, actually processing the question. “Easy choice,” Sans said and laughed. His voice was still gravelly with sleep. “Let go.”  
Papyrus did, leaning back against the couch and watching Sans catch his breath. “You are an excellent guard dog,” he said. “But quite a terrible submissive.”  
“Who said I was sub?” Sans snapped, sneering.  
Papyrus said nothing, but the slight tilt to his mouth held all the silent words.  
Sans snorted. “Whatever, Paps. You getting out your dick or what?” He braced his hands against Papyrus hips, a shark-like grin leveled at him.  
Papyrus gave him a steady stare, all traces of amusement gone. “I have a different idea,” he hummed. “You remember the ropes in the shed?”  
Sans straightened sharply like a hunting dog that had found a scent. His eyelights were bright. “Yeah?”  
“Get them.” Papyrus had barely finished the order when Sans vanished, displaced. Papyrus stood and went into the kitchen. He had gathered scissors and water and was setting them on the living room table when Sans reappeared. Papyrus looked over and rolled his eyes.  
Sans posed, ropes draped over his shoulders and around his body. “How do I look?”  
“Like someone tried to kidnap you and did a terrible job of it.” Papyrus started taking the ropes from him.  
Sans scoffed. “They could do a fantastic job and I’d still tear free.”  
“I should hope so.” Papyrus set the ropes down and started sorting through them.  
Sans sat on the couch, perched on the edge instead of his usual lazy sprawl. “You sure about this?” he asked, sounding excited and surprised. He met Papyrus look for look when the other turned away from the ropes to squint at him.  
“Yes. Am I ever not?” Papyrus griped, wary.  
Sans shrugged. “‘Course not. But you were giving me so many excuses up until now. Just wondering what changed...”  
Papyrus had to still his hands from fidgeting with the rope. It would be a dead giveaway to the ever-observant Sans. “It isn’t your concern.”  
He could feel Sans examining him, but the smaller skeleton just shrugged. “Kay. Whatever you say, Boss.”  
Papyrus’s hackles went up at the derogatory tone. He turned, eyelights sparking with annoyance, to see Sans smirking at him. Papyrus couldn’t tell if it made him feel better or worse knowing that Sans was just getting a rise out of him. “Hands.”  
Sans blinked and lifted his arms, hands close together and held out to Papyrus. Papyrus started looping the rope around his wrists, snug but not tight, until he was satisfied. He twisted a knot into place, then shifted and brought the rope up to Sans’s neck. As he started threading it through the link of his collar, he noted the faint red flush already on his partner’s face. He briefly contemplated teasing Sans for it before discarding the idea; no need to push him yet.  
He tied the rope off and leaned back. “Test it.”  
Sans did, pulling gently at first then harder, wrists bound together and unable to move further than a foot or so away from his collar. He grinned, a spark of rebellion in his red eyelights. “Not too shabby.”  
“Do not bite them or I will muzzle you,” Papyrus warned as he went for another rope.  
Sans crooned. “Don’t threaten me with a good time, Boss.” Still, he didn’t go for the ropes. Probably enjoying the light pressure too much.  
Papyrus knelt. He could sense Sans leering and preening above him, always pleased to have Papyrus at his feet in whatever way possible. Papyrus ignored him, looping the rope through his bones and around his ankles. He tested the tightness with his finger, then sat back to look at Sans.  
Sans was practically purring, a hazy look in his eyes and a loopy grin on his face. He snapped out of the stupor when he noticed Papyrus looking at him, the smile sharpening. “Am I pretty?” He posed again, albeit impeded by the ropes on his wrists.  
Papyrus felt his magic throb in his chest. He leaned into Sans’s space, hand resting on his ribs loosely as he nuzzled Sans’s cheekbone. “Beautiful,” he corrected.  
Sans chuckled low, amused. He nipped at Papyrus to get him to jerk back. “Ain’t never been beautiful in my life, but good try, you sap.”  
Papyrus grabbed the rope at Sans wrists and jerked him forward, pulling him close and leaning into his space. “Such a good liar,” he breathed and kissed him.  
He could never get over Sans’s teeth. Sure, he had his own sharp fangs, but there was something about Sans’s serrated maw that was incredibly enticing in its danger. Maybe it was the fact that Sans wasn’t gentle with his fangs, biting if Papyrus got too brazen and clashing against his mouth with reckless roughness.  
When Papyrus stood, they were both panting lightly. He took a soft breath to steady himself as he undid his pants, pulling his length free.  
Sans lit up with interest. He leaned forward eagerly, but Papyrus grabbed his collar to hold him at bay, clicking his tongue. Sans rumbled, glancing up at him in confusion and hunger.  
Papyrus pulled at him sideways until he got the hint and laid down on his side, awkwardly holding his hands near his chest and tugging at the bonds on his ankles.  
Papyrus purred, running a hand down Sans’s spine. “Good boy,” he said idly, fingers running over Sans’s tailbone and through the gathering magic in his pelvis. Sans jerked, almost kicking him. “Easy,” he murmured, fingers stirring through his magic again.  
Sans hissed. “Boss, c’mon.” Red magic gathered around Papyrus’s fingers, then collected into a form.  
Papyrus withdrew his fingers from Sans’s cunt. “You didn’t need to do that,” he said, mildly displeased. It didn’t stop him from licking the slick off his fingers.  
Sans snorted. “You know I can take it,” he griped. “Don’t pull this sissy shit with me.”  
Papyrus leaned over him, his body covering and trapping Sans. “Oh I know,” he murmured to him, pressing a feather-light kiss to his temple. “Fool.”  
Sans cried out sharply as Papyrus thrust into him. He groaned, his body lit with fire.  
Papyrus exhaled shakily. “You’re being too loud,” he admonished.  
Sans laughed. “Oh, am I? Fuck me, then, it’s not like I just got your rod shoved up my fuckin’ pussy. Your own damn fault for being so—“ He cut off into a gasp as Papyrus moved, eyelights guttering. “Shit, Paps, give a guy some warning.”  
“Like you need one,” Papyrus snorted. He eased back out, shivering at the friction.  
“Faster,” Sans pleaded.  
“You will get hurt,” Papyrus told him, moving no faster. “I need you to be able to walk in the morning.”  
“Being wetter isn’t gonna stop that. Fuck, man, c’mon.” Sans tugged at the ropes and groaned, squeezing his eyesockets shut.  
Papyrus shifted and grabbed Sans’s jaw lightly, turning his face towards him. “Look at me,” he said sternly. When Sans didn’t respond, he grabbed the ropes at his wrists and jerked on them. “Look at me!”  
Sans hissed and did. The red points of light were blown out, hazy.  
Papyrus relaxed. “I love you.” He started pushing his hips more quickly, the slide of his cock inside Sans more fluid now.  
Sans moaned. “No, Boss, don’t do this to me.” He pressed his hands against Papyrus’s chest.  
Papyrus felt like Sans should be able to feel his soul pounding just from his hands being so close. It felt like it would jump out of his ribs. He would take it out himself if Sans asked. “I love you,” he said again, voice catching.  
“Don’t.” Sans was practically whining, body jerking as Papyrus began to get more forceful, mouth agape helplessly.  
Papyrus leaned into the hands against his chest, eyes locked on Sans’s gaze. “You are so good, brother,” he murmured.  
Sans shuddered, clenching around Papyrus and sucking a breath. “Paps,” he rasped. “Please.”  
“What do you want?”  
Sans hesitated, almost lost. Papyrus could see the confusion there, the thoughts that came quickly and went just as fast, driven out of his mind by Papyrus’s movements. The noises their bodies made were loud in the quiet, bones clacking together, heavy panting, the couch protesting the abuse, and the slick sounds of Papyrus fucking into him.  
Sans broke. “Just fuck me,” he said.  
Papyrus’s mouth twitched into an almost smile. Not today, then. Someday he would get Sans to ask for what he really wanted. But not today.  
Papyrus did, bracing himself against the couch and Sans’s hands against his armor. Sans cried out with abandon, ever the shameless one, begging in soft words he would never speak outside that house. When Papyrus leaned forward and bit into his shoulder, he yelped and fought, writhing. But then he stilled, back arching with tension as he spilled around Papyrus, hitching breaths catching in his throat.  
Papyrus let him go and withdrew, taking his cock in hand. Sans was blearily content to lay there as Papyrus jacked off and came on him, dark crimson splattering over his femurs and pelvis.  
They rested for a moment, catching their breath. Papyrus let his magic dissipate and fixed his pants, then starting untying the ropes. Sans was silent during the process, eyelights still hazy and unfocused. When Papyrus gently massaged the bone where the ropes had been, he broke into soft purring.  
Papyrus almost smiled again, leaning down to kiss him. His nuzzled their nasal bones together, then stood. He tugged a blanket down over Sans and set the water from before next to him, then disappeared further into the house for a few moments.  
“Boss?”  
Papyrus was back in a flash, almost as if he also had teleportation powers. “Yes?” He approached, sitting next to Sans who still lay on the couch.  
Sans blinked at him. “...Lay down with me, dumbass,” he grumbled.  
Papyrus obeyed, nudging Sans around to make room for himself and ultimately winding up with Sans laying on top of him, both of them loosely covered by the blanket. Papyrus’s legs weren’t completely covered, but he didn’t mind.  
Papyrus picked up the untouched water and nudged Sans. “Drink.”  
Sans grumbled a tired protest.  
Papyrus nudged him again. “Bad dog. Drink.”  
Sans chuckled dryly and finally took the bottle, sitting up a little to drink from it. He tossed it to the floor and cuddled up on Papyrus again.  
Satisfied, Papyrus relaxed, doing a lazy Check on his brother.  
“Hey, Boss?” Sans said softly, ignoring the Check.  
“Hmm?”  
“...Love you, too.”  
Papyrus felt like his soul would explode. He drew his hand down Sans’s spine again, feeling him purr.


End file.
